31results about How to "Control supersaturation" patented technology

The invention relates to a surface erosion-resistant composite coating of a carbon/carbon composite, which sequentially consists of ZrC0.7/ZrC1.0/ZrC1.0+C form outside to inside. The preparation method of the surface erosion-resistant composite coating comprises the following three steps: the preparation of a basal layer ZrC1.0+C, the preparation of a middle layer ZrC1.0 and the preparation of an outer-coating layer ZrC0.7; and is characterized in that in a chemical vapor deposition furnace at normal pressure, zirconium tetrachloride is used as the zirconium source, Ar gas is used as the carrier gas, C3H6, acetylene and methane are respectively used as the carbon source gasses, Ar is used as the diluent, H2 is used as the reducing gas, and the surface erosion-resistant composite coating is obtained by deposition at the temperature of 1100-1300 DEG C. The invention has the advantages of simple process method, convenient operation, single heat, stepwise deposition preparation of the composite coating with gradient-changed carbon contents, firm combination between the coating and the basal body, no penetration crack and interlayer crack, and good coating erosion resistance and thermal shock resistance, can realize the industrialized production, and is applicable to the preparation of the erosion-resistant composite coating of the carbon/carbon composite by the chemical gas-phase permeation or the liquid-phase impregnation process.

The invention relates to a method for preparing a REBa2Cu3Ox (REBCO) high-temperature superconducting block material, in particular to a melt texture growth (MTG) method for the REBCO high-temperature superconducting block material. The MTG method for the REBCO high-temperature superconducting block material comprises the following steps of: a) mixing raw materials; b) grinding and calcining to obtain a superconducting material rough blank; c) tabletting; d) firing; and e) cooling to obtain the REBCO high-temperature superconducting block material, namely e1) cooling to buffer temperature, and preserving heat, e2) cooling to growth temperature, and preserving heat, and e3) quenching. By the method, the technical problem that the REBCO high-temperature superconducting block material fails to grow because spontaneous nucleation is generated when temperature is reduced from the maximum temperature to the growth temperature in the conventional MTG method is solved.

The invention relates to the preparation field of chemical industrial materials, and particularly relates to a preparation method of a fibrous alkali magnesium sulfate whisker. The preparation method of the fibrous alkali magnesium sulfate whisker comprises the following steps: (1) preparing a magnesium sulfate solution by using MgSO4.7H2O, stirring and adding NaOH granular caustic soda, aging for 2-24 hours at the temperature of 25 to 100 DEG C to obtain a slurry; (2) transferring the slurry obtained in the step (1) into a hydrothermal reactor, wherein the filling degree is 50-80 percent, adding 0.5-5 percent of seed crystal according to the mass of the NaOH granular caustic soda, uniformly stirring, and reacting the slurry for 2-12 hours at the temperature of 130-180 DEG C; (3) cooling after finishing the reaction of the step (2), filtering, washing and drying a obtained white turbid liquid to obtain the fibrous alkali magnesium sulfate whisker. According to the preparation method, the seed crystal is added into the reaction slurry, alkali magnesium sulfate is easily subjected to nucleus formation growth, and the preparation concentration of the reaction slurry can be relatively high; the whisker nucleation time is reduced, and the whisker growth time also can be shortened.

The invention relates to a method for preparing nanometer MgO whiskers at the low temperature and the method is that magnesium powders and amorphous boron powders are mixed according to atomic ratio of MG:B being equal to 1 to 1.5:2 and the mixture is grinded for 30 to 120 minutes for thorough mixing, and after the mixed powders are made into a lump sinter under the pressure of 5 to 10 kg/cm<3> by a press machine, the lump sinter is put into a crucible which is put into a heating zone of an evacuated tubular furnace. The evacuated tubular furnace is sealed, vacuumized to 1 to 10 Pa and filled with argon the oxygen content of which is 2 percent to 5 percent and the flow rate of the mixed gas is 5 to 20 lit. per minute to heat the sample up to 650 to 750 DEG C at the heating rate of 5 to 20 K per minute, and the sample is decreased to the room temperature at the same heating rate after the temperature is kept for 0 to 120 minutes. The surface of the sample forms nanometer MgO whiskers with various appearances and sizes. When reaching 650 DEG C, magnesium evaporates and reacts with the little filled oxygen to produce MgO vapour, and under the lower over-saturation state, MgO whiskers are deposited on a substrate. The method for preparing MgO whiskers needs temperature much lower than the previous and greatly increases the practicality of preparing MgO whiskers.

The invention discloses a method for separation of rare earth in a calcium-containing rare earth solution by precipitation. The calcium-containing rare earth solution in which the rare earth concentration ranges from 0.1 mol/L to 1.5 mol/L, the calcium ion concentration ranges from 0.1 mol/L to 1.0 mol/L, the molar ratio X of the rare earth and calcium is more than or equal to 0.7 and less than orequal to 8.0 is adopted, the rare earth in the calcium-containing rare earth solution is precipitated by bicarbonate salt, and the conditions such as temperature, pH, feeding speed in the precipitation process are adjusted and controlled according to the size of the molar ratio of the rare earth and the calcium in the solution, and the concentration of bicarbonate in the solution is adjusted to control the stability of calcium bicarbonate and the supersaturation of rare earth carbonate, so that rare earth ions precipitate to form the crystalline rare earth carbonate; and calcium ions form thesoluble calcium bicarbonate, the efficient separation of the rare earth and the calcium in the calcium-containing rare earth solution is achieved, and rare earth oxide with the purity greater than 98% is obtained.

Provided is a domestic ceramic raw material whiteness proficiency testing sample, and belongs to the technical field of interlaboratory proficiency testing. The proficiency testing sample is prepared from zirconia particles of which the content is bigger than 99% and the average particle size is smaller than 74 micrometers, and is characterized in that the zirconia particles are prepared by adopting a zirconium compound as a precursor and utilizing a chemical precipitation method through zirconium compound hydrolysis-washing-calcinating-grinding, and the whiteness proficiency testing sample is prepared from the zirconia particles through a whiteness uniformity and stability test after pelleting. The domestic ceramic raw material whiteness proficiency testing sample is high in whiteness uniformity and stability, meets the requirements of the proficiency testing sample, makes up the gap of the field of current inland domestic ceramic raw material whiteness proficiency testing, and provides technical support for developing laboratory domestic ceramic raw material whiteness proficiency testing.

The invention provides a method for preparing an acrylic resin coated nano-drug by a solid wall fiber pipe bundle crystallizer and relates to nano-drug preparation. A water bath device, a dissolving drug bottle, two peristaltic pumps, the fiber pipe bundle crystallizer, a vacuum filtration system and a refrigerator are arranged; the dissolving drug bottle is arranged in the water bath device, an inner pipe and an outer pipe are arranged on the fiber pipe bundle crystallizer, the dissolving drug bottle is connected with an inlet of the first peristaltic pump, an outlet of the first peristaltic pump is connected with an inlet of the inner pipe of the fiber pipe bundle crystallizer, an outlet of the inner pipe of the fiber pipe bundle crystallizer is connected with the vacuum filtration system, an outlet of the outer pipe of the fiber pipe bundle crystallizer is connected with an inlet of the second peristaltic pump, an outlet of the second peristaltic pump is connected with an inlet of the outer pipe of the fiber pipe bundle crystallizer, and the inner pipe of the fiber pipe bundle crystallizer is formed by micron size hollow solid wall fiber pipe bundles. The method comprises the steps of preparation of the fiber pipe bundle crystallizer: single bundles of micron size hollow solid wall fiber pipe bundles are cut and put into a sleeve, and the fiber pipe bundle crystallizer is formed; preparation of the nano-drug and coating of acrylic resin; and postprocessing.